Standard-Ii and Extended Tests of the Swiss Lct-Coil

The Swiss contribution to the international Large Coil Task was a D-shaped 2.5-m×3.5-m-bore, superconducting toroidal field coil of 8 T. The conductor was made from copper-stabilized, fully transposed NbTi filaments, cabled in three stages and cooled with pressurized supercritical helium. The testing of the six coils was successfully finished last year at Oak Ridge National Laboratory. The AC loss measurement data taken during the standard-II tests are presented. The results are compared with predictions made while designing the coil. The results of the extended-condition tests are discussed. Recently analyzed quench data, taken during the entire test period, are presented. The data showed that a fully transposed filamentary conductor with short twist pitch and well-designed resistive barriers reduces substantially the AC losses in the windings. The overall current density reached 33 A/mm2 at 8.96 T and 29.6 T/mm2 at 9.1 T in the high- and maximum-field torus tests, respectively. This demonstrated that the NbTi-based CH conductor had a sufficient current margin